Java模拟post请求上传文件

• Java代码实现

  /**
       * 模拟文件post上传
       * @param urlStr（接口地址）
       * @param formName（接口file接收名）
       * @param fileName（需要上传文件的本地路径）
       * @return文件上传到接口返回的结果
       */
  public static String uploadFile(String urlStr, String  formName, String fileName) {
      String baseResult = null;
      try {
          final String newLine = "\r\n";
          final String boundaryPrefix = "--";
          String BOUNDARY = "========7d4a6d158c9";// 模拟数据分隔线
          URL url = new URL(urlStr);
          HttpURLConnection conn = (HttpURLConnection) url.openConnection();
          conn.setRequestMethod("POST");// 设置为POST请求
          conn.setDoOutput(true);
          conn.setDoInput(true);
  
          conn.setRequestProperty("connection", "Keep-Alive");// 设置请求头参数
          conn.setRequestProperty("Charsert", "UTF-8");
          conn.setRequestProperty("Content-Type","multipart/form-data; boundary=" + BOUNDARY);
          OutputStream out = conn.getOutputStream();
          
          File file = new File(fileName);
          StringBuilder sb = new StringBuilder();
          sb.append(boundaryPrefix);
          sb.append(BOUNDARY);
          sb.append(newLine);
          sb.append("Content-Disposition: form-data;name=\""+formName+"\";filename=\""+ fileName + "\"" + newLine);
          sb.append("Content-Type:application/octet-stream");
          sb.append(newLine);
          sb.append(newLine);
          
          out.write(sb.toString().getBytes());// 将参数头的数据写入到输出流中
          
          DataInputStream in = new DataInputStream(new FileInputStream(file));// 数据输入流,用于读取文件数据
          byte[] bufferOut = new byte[1024];
          int bytes = 0;
          
          while ((bytes = in.read(bufferOut)) != -1) {// 每次读1KB数据,并且将文件数据写入到输出流中
              out.write(bufferOut, 0, bytes);
          }
          
          out.write(newLine.getBytes());
          in.close();
          
          byte[] end_data = (newLine + boundaryPrefix + BOUNDARY
                             + boundaryPrefix + newLine).getBytes();
          
          out.write(end_data);
          out.flush();
          out.close();
  
          
          BufferedReader reader = new BufferedReader(new InputStreamReader(
              conn.getInputStream()));
          String line = null;
          StringBuffer strs = new StringBuffer("");
          while ((line = reader.readLine()) != null) {
              strs.append(line);
          }
          baseResult = strs;
      } catch (Exception e) {
          baseResult = e.getMessage();
      }
      return baseResult;
  }